1. Field of the Invention
The present invention relates to ductwork for heating, ventilation and air-conditioning (HVAC) systems. More particularly, the present invention relates to register boxes as used in such systems. More particularly, the present invention relates to processes for forming such register boxes.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
To create the desired ambient conditions within a structure, a typical HVAC system is installed for circulating and/or conditioning air drawn from the interior of the structure and returned to the interior of the structure. A central unit or several units are located in or near the structure, each unit comprising a fan for air circulation and optionally comprising a heating, humidification, or cooling system for conditioning the air passing through the central unit.
To conduct air to and from each central unit, ducting is provided in the structure. The ducting includes supply-air ducts which provide conditioned air to the interior of the structure and are connected to the outlets of each central unit and return-air ducts which return air to each central unit and are connected to inlets of each central unit. Supply-air ducts typically terminate in supply-air register boxes mounted to the walls, the ceilings, or other surfaces within the interior, whereas return-air ducts typically begin at register boxes mounted to a surface within the interior, such as a wall, ceiling, or floor. There are usually many more register boxes for supplying air than for returning air, with those for returning air typically being substantially larger than those for supplying air.
To increase efficiency, building codes are being revised to require substantially airtight HVAC systems. In the past, a standard technique has been utilized for forming such sheet-metal register boxes. A form is cut from a rectangular, planar metal sheet. The form has cutouts for corners or other features to allow bending of the form into the desired shape. Cutouts define the height of the sides and an overlapping flap is formed by cutting a slot at each cut out. The sides are bent along bend lines to lie in intersecting planes so as to form an open-bottom, rectangular enclosure of a register box, with the vertical edges of the sides abutting the inside surfaces of the sides. The flap is folded around each corner that lies adjacent the outer surface of the side and then fastened to the side with rivets. In order to complete the register box, a circular duct connector or is connected to a circular cutout in the upper surface of the box. Prior art register boxes are also formed with abutting edges to form the enclosure. The abutting or overlapping edges may be fastened by adhering or by other fastening means, such as spot welding.
The method described above produces ducting enclosures that often leak conditioned air through the gaps between the edges at the corners, or, in the case of enclosures formed with multiple pieces, through the seams where the pieces are joined together. The prior-art method includes many labor-intensive steps to form the enclosures, including the cutting of the planar sheet and the fastening of the edges.
In order to achieve the requisite efficiency in compliance with building codes, insulation is used with such register boxes. The formation of the insulation of the register boxes has become somewhat of a problem. Since the boxes are conventionally made of sheet metal, such as galvanized steel or aluminum, the insulation must be applied to either or both the inside and outside of the register box either before or after it is installed. The cutting and fastening of the insulation to the box is tedious and time-consuming. As such, it is thereby rather expensive in terms of the cost of the insulation material and in terms of the amount of time required to properly insulate the register box.
The placement of insulation can be a time-consuming, hazardous, and tedious task. Typically, a large section of fibrous material requires a cutting into various shapes that fit within the interior of the register box. This fibrous material is then affixed to the walls on the inside of the register box by hand. Often, many steps are required so as to properly fit the insulation material within the register box. Furthermore, since fibrous material is being manually handled by workers, there can be exposure to airborne fibers. The cutting and fitting of the insulation material within the register box is extremely tedious and boring to workers.
In the past, various patents have issued relating to register boxes and to the insulating of such register boxes. For example, U.S. Pat. No. 3,985,158, issued on Oct. 12, 1976 to J. V. Felter, describes a box for mounting diffusers wherein the main body of the box is made of expanded plastic or similar material. One or more connection elements are molded within the walls of the box to provide for connection of the box to the building structure and to a duct and also to reinforce the box.
U.S. Pat. No. 4,735,235, issued on Apr. 5, 1988 to Anderson et al., discloses an insulated duct end system. The system includes duct assemblies and transition components for interconnecting the duct assemblies. Each duct assembly includes an insulated duct having a rigid sleeve within at least one end. Each sleeve includes an abutment ring and orifices in the ring for permitting air to flow into the insulated area to balloon the layer and improve its insulative effect.
U.S. Pat. No. 5,095,942, issued on Mar. 17, 1992 to G. C. Murphy, teaches a plastic self-insulating ductwork system. The system includes a distribution box which includes an upper portion having a plurality of walls and a bottom plate. The distribution box is joined to interconnecting duct lines by adapter conduits. The adapter conduits are adapted at one end for connection to an opening in the wall and are adapted at the other end for connection to an adjoining duct line. U.S. Pat. No. 5,219,403, issued on Jun. 15, 1993 the G. C. Murphy, discloses a similar type of self-insulating ductwork system as that of U.S. Pat. No. 5,095,942.
U.S. Pat. No. 5,658,196, issued on Aug. 19, 1997 to T. L. Swaim, provides an air duct diffuser for attachment to a ceiling grid. The diffuser includes a frame which mounts to the ceiling grid and a louver which mounts to the frame for directing diffused air within an associated airspace. A pre-formed composite housing of insulating material mounts to the frame and has punch-out duct openings of varying sizes.
U.S. Pat. No. 5,749,190, issued on May 12, 1998 to S. R. Williams, shows an HVAC register box having no welded or riveted corners and also a process for making such an HVAC register box. The register box is fabricated from a single sheet of material without cutting. The register box has superior rigidity and resistance to air leakage at the joints or corners.
U.S. Pat. No. 5,957,506, issued on Sep. 28, 1999 to M. D. Stepp, provides a sheet-metal insulated register box. The register box has an adjustable elbow fitting that is coupled directly to an air inlet panel of an air distribution register box by having roll-formed flange portions that are mated in interlocking, overlapping engagement with each other. The air inlet panel includes an outwardly flared coupling flange bordering an air inlet opening. The neck of the sheet-metal elbow includes a folded coupling flange that is dimensioned for interfitting, overlapping engagement with the outwardly-flared elbow coupling flange.
U.S. Patent Publication No. 2008/0014860, published on Jan. 17, 2008 to Heitman et al., discloses a method and apparatus for eliminating register boxes. A collar plate assembly interfaces with metal air ducts and is provided with at least one spring indentation ring to accept two or more locking springs. The locking springs are used to attach the ceiling register to the collar plate assembly. The collar plate assembly uses mounting rails that attach the assembly to either the ceiling or wall supports. A trim ring is inserted in the cutout that attaches between the collar in the ceiling so as to eliminate air leakage and so as to provide an essentially smooth flow of air from the supply duct to the inside of the structure.
U.S. Patent Publication No. 2004/0130154, published on Jul. 8, 2004 to Stepp et al., shows a substantially airtight register box for HVAC systems. The register box has a body formed from at least one planar sheet. The body has an inlet and outlet. At least one of the inlet and the outlet is formed by folding corners of the planar sheet to form planar sides that lie in intersecting planes. The enclosure is then mounted to a surface of an interior area of a structure and is connected to ducts for communicating air between the interior area at a central air-handler unit.
U.S. Patent Publication No. 2008/0045137, published on Feb. 21, 2008 F. Rosal, discloses an insulated plenum box for heating, ventilating and air conditioning duct systems. This plenum box has insulation sprayed onto either the inside or outside of the plenum box in order to match the R-value of the connecting insulated duct.
It is an object of the present invention to provide a process for forming a register box which minimizes air loss.
It is another object of the present invention to provide a process for forming a register box which improves the insulated rating of the register box.
It is another object the present invention to provide a process for forming a register box in which the register box is fire-resistant.
It is another object of the present invention to provide a process for forming a register box in which the register box is compliant with national building codes.
It is another object of the present invention to provide a process for forming a register box which allows the register box to be stackable.
It is another object of the present invention to provide a process for forming a register box which avoids the use of fibrous insulation.
It is another object of the present invention to provide a process for forming a register box which improves the health and safety to workers assembling the register box.
It is a further object of the present invention to provide a process for forming a register box in which the formed register box is very energy efficient.
It is still another object of the present invention to provide a process for forming a register box which allows inspectors to quickly ascertain that the register box is insulated.
It is still further object of the present invention to provide a process for forming a register box which does not require the alteration of the structure of the existing register box.
It is still a further object of the present invention to provide a process for forming a register box in which the process is very efficient, relatively inexpensive and efficient.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.